1. Field of the Invention
The present invention generally relates to fluorescent lamps, and in particular, to self-ballasted fluorescent lamps.
2. Description of the Related Art
Fluorescent lamps provide a number of advantages over incandescent lamps. For one thing, fluorescent lamps consume much less energy (e.g., only one-quarter to one-third of the energy) than incandescent lamps to produce the same amount of light. Plus, fluorescent lamps have much longer service lives than incandescent lamps (e.g., 10 to 15 times longer).
Referring to FIGS. 10 through 15, various conventional fluorescent lamps for use with a ceiling mounted lighting fixture are shown. The ceiling mounted lighting fixture 400 generally includes a fixture base 405 and an electronic ballast 410 mounted thereto. The ceiling mounted lighting fixture 400 may further include a cover 425 removably attached to the fixture base 405. The cover 425 has a circular shape and provides a limited height clearance in the region where a lamp unit is to be mounted. As a result, a conventional compact fluorescent lamp 490 (shown in FIG. 14) may not be suitable for use with such lighting fixtures, as illustrated in FIG. 15. One type of conventional fluorescent lamp for use with the ceiling mounted lighting fixture 400 is a circular fluorescent lamp tube 415 which is retained within the fixture base 405 by a number of resilient lamp holders 420. Another type of lamp unit currently used with the ceiling mounted lighting fixture 400 is illustrated in FIGS. 12 and 13, which employs two fluorescent lamps 450-1 and 450-2, each lamp having twin U-shaped lamp tubes or quad-straight lamp tubes.
There are a number of disadvantages associated with the above-mentioned conventional fluorescent lamps 415, 450 and 490 for use with the ceiling mounted lighting fixture 400. For example, the circular fluorescent lamp tube 415 shown in FIGS. 10 and 11 may not provide evenly distributed lighting over the light fixture cover 425, possibly causing dim center region to appear on the cover 425 where the illumination is weak. Similarly, the two fluorescent lamp unit configuration shown in FIGS. 12 and 13 may also cause dim regions to appear on the cover 425 since illumination is provided only in the areas proximal to the lamp units 450-1 and 450-2. Another disadvantage associated with the conventional fluorescent ceiling lighting system, illustrated in FIGS. 10 through 13, is that because the electronic ballast is housed within a separate ballast housing unit 410, the ballast unit 410 must be replaced separately from the fluorescent lamp, increasing the cost and effort associated with maintaining the ceiling lighting system.